I have a Grundfos dosing pump that operates at 0.15 gallons per hour,so just drops at a time. The liquid flows through flexible hose. I don't need actual flow, just indication that liquid is moving. I could live with just visual indication like those little paddle wheel deals, or the things with beads in them, but I would love to be able to send a go/no go signal to a controller if I could. Any ideas are appreciated.